Optionally use neovim's api-highlights (#2169)

autoload/ale/highlight.vim

@@ -26,6 +26,41 @@ endif
 let s:MAX_POS_VALUES = 8
 let s:MAX_COL_SIZE = 1073741824 " pow(2, 30)
 
+" Check if we have neovim's buffer highlight API
+"
+" Below we define some functions' implementation conditionally if this API
+" exists or not.
+"
+" The API itself is more ergonomic and neovim performs highlights positions
+" rebases during edits so we see less stalled highlights.
+let s:nvim_api = exists('*nvim_buf_add_highlight') && exists('*nvim_buf_clear_namespace')
+
+function! ale#highlight#HasNeovimApi() abort
+    return s:nvim_api
+endfunction
+
+function! ale#highlight#nvim_buf_clear_namespace(...) abort
+    return call('nvim_buf_clear_namespace', a:000)
+endfunction
+
+function! ale#highlight#nvim_buf_add_highlight(...) abort
+    return call('nvim_buf_add_highlight', a:000)
+endfunction
+
+function! s:ale_nvim_highlight_id(bufnr) abort
+    let l:id = getbufvar(a:bufnr, 'ale_nvim_highlight_id', -1)
+
+    if l:id is -1
+        " NOTE: This will highlight nothing but will allocate new id
+        let l:id = ale#highlight#nvim_buf_add_highlight(
+        \   a:bufnr, 0, '', 0, 0, -1
+        \)
+        call setbufvar(a:bufnr, 'ale_nvim_highlight_id', l:id)
+    endif
+
+    return l:id
+endfunction
+
 function! ale#highlight#CreatePositions(line, col, end_line, end_col) abort
     if a:line >= a:end_line
         " For single lines, just return the one position.
@@ -49,12 +84,90 @@ endfunction
 
 " Given a loclist for current items to highlight, remove all highlights
 " except these which have matching loclist item entries.
+
 function! ale#highlight#RemoveHighlights() abort
-    for l:match in getmatches()
-        if l:match.group =~# '^ALE'
-            call matchdelete(l:match.id)
+    if ale#highlight#HasNeovimApi()
+        if get(b:, 'ale_nvim_highlight_id', 0)
+            let l:bufnr = bufnr('%')
+            " NOTE: 0, -1 means from 0 line till the end of buffer
+            call ale#highlight#nvim_buf_clear_namespace(
+            \   l:bufnr,
+            \   b:ale_nvim_highlight_id,
+            \   0, -1
+            \)
         endif
-    endfor
+    else
+        for l:match in getmatches()
+            if l:match.group =~# '^ALE'
+                call matchdelete(l:match.id)
+            endif
+        endfor
+    endif
+endfunction
+
+function! s:highlight_line(bufnr, lnum, group) abort
+    if ale#highlight#HasNeovimApi()
+        let l:highlight_id = s:ale_nvim_highlight_id(a:bufnr)
+        call ale#highlight#nvim_buf_add_highlight(
+        \   a:bufnr, l:highlight_id, a:group,
+        \   a:lnum, 0, -1
+        \)
+    else
+        call matchaddpos(a:group, [a:lnum])
+    endif
+endfunction
+
+function! s:highlight_range(bufnr, range, group) abort
+    if ale#highlight#HasNeovimApi()
+        let l:highlight_id = s:ale_nvim_highlight_id(a:bufnr)
+        " NOTE: lines and columns indicies are 0-based in nvim_buf_* API.
+        let l:lnum = a:range.lnum - 1
+        let l:end_lnum = a:range.end_lnum - 1
+        let l:col = a:range.col - 1
+        let l:end_col = a:range.end_col
+
+        if l:lnum >= l:end_lnum
+            " For single lines, just return the one position.
+            call ale#highlight#nvim_buf_add_highlight(
+            \   a:bufnr, l:highlight_id, a:group,
+            \   l:lnum, l:col, l:end_col
+            \)
+        else
+            " highlight first line from start till the line end
+            call ale#highlight#nvim_buf_add_highlight(
+            \   a:bufnr, l:highlight_id, a:group,
+            \   l:lnum, l:col, -1
+            \)
+
+            " highlight all lines between the first and last entirely
+            let l:cur = l:lnum + 1
+
+            while l:cur < l:end_lnum
+                call ale#highlight#nvim_buf_add_highlight(
+                \   a:bufnr, l:highlight_id, a:group,
+                \   l:cur, 0, -1
+                \   )
+                let l:cur += 1
+            endwhile
+
+            call ale#highlight#nvim_buf_add_highlight(
+            \   a:bufnr, l:highlight_id, a:group,
+            \   l:end_lnum, 0, l:end_col
+            \)
+        endif
+    else
+        " Set all of the positions, which are chunked into Lists which
+        " are as large as will be accepted by matchaddpos.
+        call map(
+        \   ale#highlight#CreatePositions(
+        \       a:range.lnum,
+        \       a:range.col,
+        \       a:range.end_lnum,
+        \       a:range.end_col
+        \   ),
+        \   'matchaddpos(a:group, v:val)'
+        \)
+    endif
 endfunction
 
 function! ale#highlight#UpdateHighlights() abort
@@ -79,17 +192,14 @@ function! ale#highlight#UpdateHighlights() abort
             let l:group = 'ALEError'
         endif
 
-        let l:line = l:item.lnum
-        let l:col = l:item.col
-        let l:end_line = get(l:item, 'end_lnum', l:line)
-        let l:end_col = get(l:item, 'end_col', l:col)
+        let l:range = {
+        \   'lnum': l:item.lnum,
+        \   'col': l:item.col,
+        \   'end_lnum': get(l:item, 'end_lnum', l:item.lnum),
+        \   'end_col': get(l:item, 'end_col', l:item.col)
+        \}
 
-        " Set all of the positions, which are chunked into Lists which
-        " are as large as will be accepted by matchaddpos.
-        call map(
-        \   ale#highlight#CreatePositions(l:line, l:col, l:end_line, l:end_col),
-        \   'matchaddpos(l:group, v:val)'
-        \)
+        call s:highlight_range(l:item.bufnr, l:range, l:group)
     endfor
 
     " If highlights are enabled and signs are not enabled, we should still
@@ -111,7 +221,7 @@ function! ale#highlight#UpdateHighlights() abort
             endif
 
             if l:available_groups[l:group]
-                call matchaddpos(l:group, [l:item.lnum])
+                call s:highlight_line(l:item.bufnr, l:item.lnum, l:group)
             endif
         endfor
     endif